Pregnant HIV-1 infected women and their newborns will be subjected to a variety of virologic and immunologic evaluations. WE plan to correlate the results generated from this study of these individuals with the pregnancy outcome. This includes: a) the quantity of HIV in PBMC and plasma; b) the functional characteristics of the maternal and neonatal HIV isolates; c) the presence of CTL against autologous cells expressing gag or env of IIIb RF; d) the presence of HIV-peptide specific lymphoproliferation and/or lymphokine release; e) the titer of maternal serum neutralizing activity against autologous isolates; f) the presence of maternal antibodies which could compete with neutralizing monoclonal antibodies (anti-V3, type-specific and anti-CD4 binding site, group specific) for binding to the gp120 of JRCSF (an MN-like isolate); g) the titer of maternal ADCC (versus IIIb); h) evidence of placental inflammation and HIV infection of dissociated trophoblasts; and i) the maternal and neonatal HLA types. The correlation of assay parameters generated on the entire cohort of mother-child pairs may identify factors which increase or decrease the rate of HIV transmission. Biologic HIV-1 clones will be generated for use in assays (neutralization, ADCC, and CTL) which measure responses to autologous viral isolates. This aspect of the study will help elucidate the role of viral escape mutants in HIV transmission.